Field of the Disclosure
Aspects of the present disclosure relate generally to wireless communications systems, and more particularly, to avoiding unnecessary protocol data unit (PDU) transmissions, for example, based on a reorder timer expiring.
Description of Related Art
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
A wireless communication network may include a number of eNodeBs (eNBs) that can support communication for a number of user equipments (UEs). A UE may communicate with an eNodeB via the downlink and uplink. The downlink (or forward link) refers to the communication link from the eNodeB to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the eNodeB.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
For example, in LTE, a UE can aggregate connections with a plurality of eNodeBs or other access points, using dual-connectivity (or multiple-connectivity) with multiple eNodeBs and/or related cells, traffic aggregation (e.g., radio access network (RAN) aggregation or other network level aggregation) with one or more eNodeBs and one or more other types of access points (e.g., a WiFi hotspot). The UE can receive protocol data units (PDU) over the connections at one or more network layers, and can order the PDUs based on a sequence number. A PDCP timer can be initialized to manage cases where a PDU may not be received. Based on a determined expiration of the PDCP timer without receiving the PDU, all service data units (SDU) received for a PDU (e.g., at a lower network layer) are flushed to the network layer (e.g., provided to the network layer and deleted from the lower network layer memory). In some cases, however, the missing SDUs may still be transmitted to the UE though the UE has given up on receiving the PDU at the network layer, and discards the SDUs received at the lower network layer when/if subsequently received.